The present invention relates generally to a process for preparing a tobacco blend, and to apparatus for preparing a tobacco blend.
A plurality of different tobacco blends each containing at least two different types of tobacco are available on the market. The various tobacco blends have different recipes for blending the different tobacco types. Tobacco types can be, by way of example, Burley, Flue Cured, Oriental, Bright and Reconstituted tobacco. Burley, Flue Cured and Oriental tobacco are specific sorts of tobacco, while Bright tobacco is a pre-blend of Flue Cured and Oriental tobacco. These tobaccos may be used in pre-blended form and processed as pre-blend. The two components contained in this pre-blend are considered as behaving equally throughout the process, for example with regard to cutting, expansion and drying. Reconstituted tobacco denotes tobacco made from tobacco parts that were collected during previous handling of tobacco, for example during the cutting.
From WO 2007/134879 a flash dryer for tobacco is known comprising a drying channel having two or more inlets arranged at different levels along the drying channel. Tobaccos having different moisture contents can be fed into the process gas flowing through the drying channel so that the tobacco can be dried.
Usually, different tobacco types are treated individually with respect to moisture, temperature, impregnation, casing, cutting width, and so on, in accordance with their specific characteristics and needs. This individual treatment of the respective tobacco types also applies for the expansion and drying steps, in order to optimize the specific characteristics of each tobacco type. Only then blending of different tobacco types is performed in a separate step in accordance with the respective blending recipe. Blending may occur prior to storage so that the respective blends may be stored in boxes or silos which are opened at the time the blend is further processed, for example in a cigarette making process. Alternatively, blending may be performed at the time the tobacco is further processed, so that the different tobacco types are stored in boxes or silos unblended.